Shot cleaning method for heat exchangers



Dec. 13, 1966 v. KQLLERUP 3,291,197

SHOT CLEANING METHOD FOR HEAT EXCHANGERS Original Filed June 11. 1965R/NSE L/OU/D 0mm /3 INVENTOR PRESSUR/ZED Vagn Kol/erup WATER /2 R/NSE BYORNEYS United States Patent 3 Claims: or. 165-1) The present inventionis a continuation of my earlier application Serial No. 287,013, filed onJune 11, 1963, now abandoned.

The present invention relates to improvements in a method of operatingball or shot-cleaning installations associated with heat exchangers orsimilar units and in an arrangement for ball or shot'cleaninginstallations operating according to the inventive method.

In boiler plants and similar heating exchangers having heating surfaceswhich are exposed to deposits of fiyashes and soot, the heating surfacesmay be cleaned by steel balls of 4 to 6 mm. being caused to cascadedownwardly over the heating surfaces thereby dislodging and removing thedeposits because of both the vibration produced and the impurities beingdirectly carried away by the gravitating particles or balls.

Having passed the heating surfaces, the balls are mixed wit-h soot andfiyashes so that they must be cleaned before reuse. This cleaningprocess is, in the prior art shot-cleaning installations, effected bymeans of an air flow which first carries the accumulations along withthe shot and subsequently passes one or more cyclones, wherein the dustis again separated from the air. A dust separated off is carried away ina dry condition.

Having been subjected to the above-mentioned cleaning process, the ballsare conveyed upwards to an upper storing container so as to be ready foranother passage through the boiler plant. This return or upwardtransportation of the balls may be performed mechanically by means of .alift, or the balls may be carried upwardly by an airflow from ahigh-pressure blower.

In the known shot-cleaning installations, the separation of soot andashes from the shot collected after the fall through the plant causessome diificulty. No satisfactory solution has so far been suggested forthe removal of impurities present in a dry state. It is true that theycan be discharged through the funnel of the boiler plant, but this isfrom. .a general hygenic view not at all satisfactory. It is thereforean object of the present invention to overcome the above-mentioneddifficulties.

Thus, the invention relates to a method of operating shotorball-cleaning installations associated with heat exchangers or similarunits, where the balls are periodically supplied from an upper containerto the unit, and having passed such unit, the balls are directed to alower collecting container, from which, after separation from the sootand ashes sticking thereto, they are returned to the upper container forreuse. The characteristic feature of the inventive method resides inusing a liquid flow for the separation of the dirt from the balls aswell as for the transportation of the balls up to the upper container.

An installation operating according to the inventive method may besimpler in design than the prior art shotcleaning installations wherethe dirt is removed from the balls by means of a current of air. Thereis a. special advantage in the inventive method in that the dirtseparated from the balls is present in a wet condition, e.g., suspendedin Water, so that instead of being discharged 3,251,197 Patented Dec.13, 1966 ICC? in the atmosphere, it can be discharged through, forexample, a convenient sewage duct.

It is preferable that, between subsequent passages through the heatexchanger, the balls be stored in a liquid in the lower container.Thereby, drying of the balls is superfluous which would otherwise berequired in order to prevent the balls from rusting onto one an-' other.

The liquid used in the invention is advantageously alkalized water. Insuch case, the balls cascading downwardly through the heat exchanger mayhave a neutralizing effect on any acidic soot deposits particularly ifthe balls are thoroughly wet during the fall. With a view thereto, theliquid or part thereof used for conveying the balls upwardly may bedirected through the heat exchanger or the corresponding unit togetherwith the balls when the cleaning is performed.

Further, the invention relates to a ballor shot-cleaning installationworking according to the above-explained method and which comprises oneor more upper ball delivery containers and one or more lower collectingcontainers having an ejector for conveying the balls to the uppercontainer or containers. The characteristic of the device according tothe invention is that the collecting container or each of suchcontainers comprises, in addition to the liquid-operated ejector at thebot-tom, one or more rinsing liquid inlets and one or more outlets fordischarging the rinsing liquid containing soot and ashes from the ballsfalling through the liquid. During the passage downward through thecollecting container, the cleaning balls coming from the heat exchangerencounter an upwardly directed liquid fiow, e.g., a water flow, thevelocity of which is slightly lower than the falling velocity of theballs in water. The liquid flow will therefore, carry off the sootparticles and other impurities carried from the heating surfaces by theballs. The impurities practically always have a specific gravity lessthan that of the balls so that their falling velocity in the liquid willalso be lower than that of the balls. Thus, it is possible to obtain, inthe collecting container. an effective separation of soot and ashes fromthe cleaning balls, and the dirt separated off will be carried away bythe flow of rinsing liquid.

An embodiment of the cleaning plant comprising the arrangement accordingto the invention will in the following be described in detail withreference to the accompanying drawing which illustrates the invention insection.

The unit to be cleaned, e.g., the heating surfaces of a boiler plant hasbeen indicated purely diagrammatically and is noted by referencenumeral 1. The ball-cleaning installation as such consists essentiallyof an upper container 2 for delivering cleaning balls to the unit 1 anda lower container '3 for collecting the balls and dirt coming from saidunit. If so desired, the installation may comprise a plurality of uppercontainers 2 and/or a plurality of lower containers 3. The cleaningballs are delivered from the bottom of the upper container 2 through apipe 4 having a spreader body 5 and fall through the unit being cleanedto a collecting hopper 16 and a pipe 6 into the lower container 3. Thislatter container comprises an inlet for rinsing liquid, e.g., alkalizedwater, flowing upwardly through the container and in so doing encountersthe falling balls.

The pipe 6 is in communication with the lower container via a collectingbox 8 under which a short tube or socket 9 leads into the container 3.Through the same socket, rinsing liquid flows out of the container 3 asindicated by arrows, and the supply of rinsing liquid is so adjustedthat the upwards velocity (indicated by small arrows) of the rinsingliquid within the socket 9 is lower than the falling velocity (indicatedby the single broken arrow) of the balls 17 in the liquid. Thereby theliquid flow will carry dirt away from the balls but it will not preventthe latter from falling down to the bottom of the collecting container3. The used rinsing liquid flows through the collecting box 8 into anoutlet 10 which in the interest of safety may be provided with a balltrap 11 from which the impurified rinsing liquid can be directed to asewer or filtering means if it is desired to reuse the liquid.

In the lower part of the collecting container 3 there is built in aliquid-operated ejector 12 which in an outlet pipe 13 produces a liquidflow sufficient for carrying the clean balls away and conveying them upto the upper container 2 to which the pipe 13 connects, as indicated bythe series of arrows. The lower part of collecting container 3 may beprovided with a drainage and rinsing pipe 14 through which impurifiedrinsing liquid may be directed to the sewer.

In the upper container 2 the liquid used for rinsing the balls has arule to be separated from the balls prior to their being delivered tothe unit 1. This separation may be effected by means of a strainer plate18 and the liquid may leave the container through an outlet 15. Thelevel of the liquid 19 in the upper container would be largelydetermined by the opening of the outlet 15.

The equipment, such as liquid pumps and operating handles required foroperating the plant, is, in the interest of clarity, left out of thedrawing.

The present invention may be embodied in other specific forms withoutdeparting from the spirit or essential characteristics thereof. Thepresent embodiment is therefore to be considered in all respects asillustrative and not restrictive, the scope of the invention beingindicated by the appended claims rather than the foregoing descriptionand all changes which come within the meaning and range of equivalencyof the claims are therefore to be embraced therein.

What is claimed is:

1. In the method of cleaning surfaces of gas swept transmission units bymeans of solid cleaning shot which are periodically delivered from anupper container so as to rebound by gravity against said surfaces forloosening dirt particles therefrom, and then pass to a lower collectingcontainer from which the cleaning shot are returned to said uppercontainer, the step of using a first liquid fluid flow for separatingoff and carrying away the dirt particles from said cleaning shot and asecond liquid fluid flow for returning the cleaning shot to the uppercontainer, said first liquid fluid flow being directed against the flowof said shot as they are collected, said liquid fluid having a velocityless than the velocity of the falling shot in the liquid but greaterthan the velocity of said dirt particles.

2. A method of cleaning gas swept transmission surfaces according toclaim 1 wherein the cleaning shot between passages through said unit arestored below the level of a liquid supply in the lower collectingcontainer.

3. A method of cleaning gas swept heat transmission surfaces accordingto claim 1 wherein at least part of the liquid fluid used for returningthe cleaning shot to the upper container is delivered from saidcontainer to the heat transmission surfaces together with said cleaningshot.

References Cited by the Examiner UNITED STATES PATENTS 1,795,348 3/1931Schmidt 165 2,670,723 3/1954 Clarkson -95 3,062,508 11/1962 Braddon165-95 FOREIGN PATENTS 525,076 12/1953 Belgium.

ROBERT A. OLEARY, Primary Examiner.

C. SUKALO, Assistant Examiner.

1. IN THE METHOD OF CLEANING SURFACES OF GAS SWEPT TRANSMISSION UNITS BYMEANS OF SOLID CLEANING SHOT WHICH ARE PERIODICALLY DELIVERED FROM ANUPPER CONTAINER SO AS TO REBOUND BY GRAVITY AGAINST SAID SURFACES FORLOOSENING DIRT PARTICLES THEREFROM, AND THEN PASS TO A LOWER COLLECTINGCONTAINER FROM WHICH THE CLEANING SHOT ARE RETURNED TO SAID UPPERCONTAINER, THE STEP OF USING A FIRST LIQUID FLUID FLOW FOR SEPARATINGOFF AND CARRYING AWAY THE DIRT PARTICLES FROM SAID CLEANING SHOT AND ASECOND LIQUID FLUID FLOW ARE RETURNING THE CLEANING SHOT TO THE UPPER